The present invention is directed to an explosive powder actuated setting device with a driving piston axially movably displaceable within a barrel in a piston guide. The piston guide has a recess open radially inwardly toward the piston. A braking ball is located within the recess in contact with the piston and a spring is located in the recess in contact with the braking ball.
In known explosive powder actuated setting devices, the explosive force is transmitted to a fastening element by a driving piston. The driving piston, supported in a piston guide, is driven through a barrel in the guide from a ready-to-fire position into a fired position. After the setting process is completed, the driving piston must be returned to the ready-to-fire position. Holding means insure that the driving piston is retained in the ready-to-fire position until the holding force is exceeded by the explosive force.
A setting device is disclosed in DE-PS No. 1 058 950 where the holding means is a spring-loaded braking ball constantly pressed against a shank of the driving piston. In the ready-to-fire position of the driving piston, the braking ball engages in an annular groove in the piston shank.
One disadvantage of such known holding means is that the holding force continues to act as the driving piston is returned into the ready-to-fire position and, as a result, interferes with the return of the piston.